$ { \left[\begin{array}{r}{1} \\ {0} \\ {-1}\end{array}\right]-\left[\begin{array}{r}{-2} \\ {1} \\ {-1}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{r}{1}-{-2} \\ {0}-{1} \\ {-1}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{3} \\ {-1} \\ {0}\end{array}\right]}$